The Department of Health and Social Care has urged people to get their booster vaccine by December 11 to give them “very high protection against Covid-19 by Christmas Day”.
Research has shown that two weeks after a booster, people have a very high level of protection from getting a symptomatic case.
It comes as 16 of the UK’s biggest charities encourage vulnerable people to take up the offer of the jab.
Health Secretary Sajid Javid said: “With winter approaching, it’s so important that those who are at risk from the virus are protected in order to keep themselves safe.
“The vaccines are safe and effective and are helping us build a wall of defence against Covid-19. Please come forward for yours as soon as you can.”
So far about 16 million people have had a booster vaccine across Britain.